Switch



Feb. 18, 1947. w. c. FURNAS 2,416,253

' SWITCH Filed Nov. 22, 1943 s Sheets-Sheet 1 INVENTOR.

. ATTORNEYS.

' Feb. 18 1947. FURNAS 2,416,253

SWITCH Filed Nov. 22, 1943 3 Sheets-Sheet 2 INVENTOR.

Feb. 18 1947. w. c. FuF'NAs 2,416,253

' Q v SWITCH Filed Nov. 22, 1943 s Sheets-Sheet s 3/ i a: !.3- a0INVENTORY Patented Feb. 18, 1947 SWITCH William C. Furnas, Batavia,

111., assignor to Furnas Electric Company, Batavia, 111., a corporationof Illinois Application November 22, 1943, Serial No. 511,221

13 Gla-ims. (Cl. 290-424) This invention relates generally toimprovements in switches, and relates more specifically to'improvementsin the construction and operation of combined manually actuable andautomaticaliy operable electric switch assemblages.

The primary object of-the present invention is to provide a: new anduseful electric switch assemblage which is simple and compact inconstruction, and which is also extremely reliable and efficient in use.

Many different types of electric switch mechanisms for diverse purposes,have heretofore been proposed and used extensively, and in some of theseprior switch structures provision has been made for automaticallyinterrupting the electric circuits in case of dangerous overloadingthereof. Thermal overload devices of various kinds, whereinthe circuitis broken under overload conditions,

' by means of a heating element or coil coacting with a solder pot andratchet mechanism for releasing the movable contacts for quick opening,have also been previously used; and in some of these prior thermaloverload switches, the overload release coacted with the same switchcontacts which were normally manually actuable to open and close thecircuit. While a number of these prior combined manually manipulable andthermal overload operable switch assemblages were quite satisfactory inuse, most of them were unduly complicated unreliable in. operation, and.required: intricate and sensitive mechanisms which were costly toconstruct, diiiicult to assemble, and which could not be repeatedlyoperated for long: periods of time and under severe conditions. withoutrequiring replacement of parts resuiting in loss of valuable till e. tis also necessary in. thermal overload sw ches of this class, to.provide means for promptly and safely restoring the. switch to normal byresetting the overload. device after actuation thereof, most of the;prior assemblages lacked simple and conveniently manipulable means forso doing, so that all of the previous thermal overlcad switch assembliesembodied one or more highly objectionable features.

It. is therefore a more specific object of my present invention toprovide an improved combined' thermal overload and switch. devicewherein all of the above mentioned objectionable features areeliminated, and which is always trip free?" for operation of the thermaloverload mechanism.

Another specific object of this invention is to provide. a sturdyelectric switch in which the same contacts are operable to control acircuit, both normally and under emergency ccnditions, with the aid ofcommon actuating means, and wherein. the operating member need merely bepushedorstruck in order tointerrupt the circuit.

A further. specific object of the invention is to provide a combinedmanually actuable electric switch and thermal overload device, whereinthe normal actuator for the switch is also utilized to effect promptresetting of the overload device after operation thereof, and in whichnormal use of the switch actuator in no way interferes with properfunctioning of the device.

Still another specific object of the present invention is to provide animproved overload tripped switch assemblage for electric circuits, whichis extremely compact and durable in structure, and all parts of whichare normally thoroughly concealed and protected while being readilyaccessible for inspection.

An additional specific object of my invention is to provide an improvedelectric switch which is shock resistant and water-proof, and which canbe manufactured at moderate cost so as to withstand severe service for along period of time.

These and other specific objects and advantages of the invention will beapparent from the following detailed description.

A clear conception of the several features constituting my presentimprovement, and of the construction and operation of a combinedmanually operable switch and thermal overload device ernbcdyin'g theinvention, may be had by referring to the drawings accompanying andforming a part of this specification wherein like reference charactersdesignate the same or similar parts in the various views.

Fig. 1 is a central section through the support ng bracket and enclosingcasing and an offcenter scction through the overload device and contactmechanism, of one of the improved switches, showing the overload slideset and the switch contacts in closed position;

Fig. 2 is a similar section through the switch assemblage, showing theoverload slide still set and the switch contacts in open position;

Fig. 3 is another similar view of the switch mechanism, showing theoverload slide tripped so as to place the switch contacts in openposition, while the normal switch actuating elements are in contactclosed position;

Fig. 4 is a transverse section through the switch assembly, taken alongthe line l l of Fig. 1;

Fig. 5 is an inside View of the supporting bracket of the switchassemblage, showing the pivotal mounting for the actuating wedge insection;

Fig. 6 is an enlarged fragmentary transverse section through thelatching and release mechanism of the thermal overload device;

Fig. '7 is a similarly enlarged fragmentary longitudinal section throughthe latching and release mechanism of the thermal overload device; and

Fig. 8 is a simple wiring diagram showing a typical electric circuitadapted to be opened and closed with the aid of the improved switchmechanism.

While the improved features have been shown and described herein asbeing embodied in a direct current switch assemblage, it is not mydesire or intent to thereby unnecessarily restrict the scope or utilityof the improvements which are adapted for more general application toalternating current control switches as well.

Referring to the drawings, the present improved electric switchmechanism comprises in general, a rigid mounting or supporting bracketI; a combined overload and switch contact carrier frame Ii detachablysecured to the bracket I 0 by means of screws I2; two pairs of fixedcontacts I3 rigidly secured to the frame II in laterally spacedrelationship; two corresponding movable bridge contacts I4 formed ofconducting material and biased toward the adjacent fixed contacts I3 byhelical compression springs I5, and being mounted upon reciprocableparallel stems I6 formed of insulating material and slidably coactingwith slots in the frame I I; a thermal overload device of the solder pottype also carried by the frame II and having a ratchet releasecooperable with a slide I! which is movable along the frame II in adirection parallel to the contact carrier stems, the slide I1 beingprovided with transverse fingers I8 movable in alinement with the stemsI6; a helical compression spring I9 coacting with an end of the slide I!and reacting against a transverse yoke 20 secured to the frame II, thisspring constantly tending to urge the slide I'I toward contact openingposition; a tapered element or wedge 2I movable into and out of the gapbetween the fingers I8 and the adjacent ends of the contact carrierstems It, by means of a reciprocable rod 22 and a manipulating knob 23;and a closure cover or housing 24 detachably secured to the bracket I 0by screws 25.

The mounting or supporting bracket I0 may be formed by casting orotherwise, and is provided with threaded openings 26 adapted forattachment of the electrical conductor conduits, and also has integralattaching flanges 2'7, see Figs. 4 and 5. The main bracket I 0 isfurthermore provided with a waterproof seal 28 embracing the rod 22, andwith an annular sealing gasket 29 against which the housing 24 may beforced by the screws 25 so as to provide a moisture-proof enclosure forthe thermal overload and switch mechanisms, as illustrated in Figs. 1 to5, inclusive. The closure housing 24 is, however, readily removable soas to reveal the normally concealed mechanism for inspection, and thebracket I0 may obviously be suspended in any desired position.

The normally concealed frame movably attached to the bracket the screwsI2, is formed of durable insulating material, and is provided with twoseparate chambers within which the two sets of fixed and movable switchcontacts I3, I4 are confined. As previously indicated, the two movablebridge contacts I4 are constantly urged toward the adjacent stationarycontacts I3 by means of helical II which is re- Ill by means ofcompression springs I5 as depicted in Figs. 1 to 4 inclusive, and thesesprings I5 surround the inner ends of the movable contact supportingbars I6 and are seated in sockets formed in the central transverse wall30 of the frame II. The parallel contact supporting bars I6 are formedof bars of suitable insulating material and have their outer endschamfered and pointed as shown 4 in Fig. 1, for proper cooperation withthe slide fingers I 8 and with the wedge 2 I.

The thermal overload device which is also carried by the frame II, is ofthe type disclosed in Patent No. 2,296,157, granted September 15, 1942,being shown in detail in Figs, 1, 2, 3, 6 and 7, and comprises a ratchetwheel 3i having a solder pot 32 formed integral and concentrictherewith; a heating coil 33 surrounding the solder pot 32 and beingconnected in series with one of the fixed contacts I3; a fixed shaft 34permanently secured to the center wall 30 of the frame I and havingtherein annular grooves 35 containing solder slugs with which the pct 32coacts; a pawl 36 cooper-able with the teeth of the ratchet wheel 3| andbeing resiliently mounted upon the reciprocable slide l1; and thecompression spring I9 which is cooperable with the end of the slide I!as illustrated in said patent, so as to con stantly urge the fingers l8toward the outer ends of the movable contact carrier bars or stems I3.

The ratchet wheel BI is normally retained within the path of movement ofthe pawl 36 by a retainer 37, and while the wheel 3i is normallysoldered to the fixed shaft 3 1 by means of the solder slugs disposedwithin the grooves 35, the coil 33 will become heated under overloadconditions and will melt the solder and thereby release the ratchetwheel 3I for free rotation about the fixed shaft 34. The pawl 36 isconstantly urged toward the ratchet wheel 3| by means of a small spring38 as shown in Figs. 6 and 7; and the slide I1 is formed of wearresistant material and is guided along the frame II for movementparallel to the switch contact carrying stems It by means of a removableplate 39. The fingers I8 and the transverse yoke 20 against which thetripping spring I 9 reacts, may be formed of metal stampings; and whilethe pawl 33 normally coacts with the fixed ratchet wheel 3| to compressthe spring I9 and hold the fingers I8 out of the normal range ofmovement of the outer ends of the contact stems I6 as in Figs. 1 and 2,release of the wheel 3I due to overload conditions will cause the springI3 to trip the slide I1 and will open both of the movable contacts I4 asshown in Fig. 3.

The tapered block or wedge 2| which is movable transversely of thedirection of travel of the stems I6 and slide H, by means of the rod 22and knob 23, may be formed of hard rubber or other suitablewear-resistant material, and has two oppositely inclined wedge surfacesof different lengths. This wedge 2I is disposed within a cavity in thebracket Ill and is normally movable into and out of the gap between thefingers I8 and the outer ends of the movable contact carrier stems I6,by means of the rod 22 and knob 23, as will be noted from Figs. 1 and 2.In order to shield the wedge H from the fixed contact terminal screws40, an insulating shield 4I may be provided, see Figs. 1 to 4 inclusive.The wedge 2I coacts with helical compression springs 42 confined withinrecesses in the bracket I0, and is pivotally mounted upon the reducedinner end portion 43 of the actuating shaft 22 as indicated in Fig. 5.The shorter taper of the wedge 2I is normally adapted to coact with theouter chamfered ends of both contact stems I6 when the button or knob 23is pushed inwardly, so as to simultaneously open both movable contactsI4, as shown in Fig. 2; and when the knob 23 and wedge 2I are pulledoutwardly, the springs I5 will simultaneously close both of the movablecontacts I4. However, when the wedge 2| is withdrawn and the overloaddevice. becomes. active as in Fig. 3,- then the fingers: l8 are broughtinto. engagement withtheouter ends of both stems 1 [6, therebyautomatically opening both movable contacts M and breaking the circuit:through both sets of-fiXed and: movable contacts l3, l4; and the longertaper of the wedge- 2| may thereafter be utilized toresetitheoverloaddevice:

Theflexible. suspension of the. wedge 2| upon the actuating rod or shaft22, will permit the wedge toa fioat and properly contact both of thestems lfi and fingers I8iwithout undesirably stress- 'tacts closedposition, the rod is provided with an annular groove as as indicated inFigs. 1 and 3. The balls 45 are pressed. towardv the rod 22 by means ofsprings 47, and are removably confined within a'bored' socket in thebracket ill by a screw 48*. The bracket lb may'also be provided w th oneor more index'plates 49 for indicating on and. off movement of the rod22. and knob 23', and allassembly screws of the mechanism ma be providedwithlock washersfor preventing loosening thereof. due to shockor'vibration.

-'l he improved two pole switch and overload protective assemblagemaybeapplied to a direct current electric circuit in. the manner showndiagrammatically in Fig; 8', and the conductors leading to and fromtheswitch mechanism may be extended through moisture-proof conduitsconnected to the threaded bracket openings 26. After properinstallationof the assemblage in an electric circuit, the manuallymanipulable knob 23- and rod 22 may be utilized to make or break 7 thecircuit, without interference by the overload protective device, bymerely pushing or pulling on the knob 23. When this knob'has been pulledout as in Fig. l, the springs it are active to close both sets of switchcontacts 1% l4 and the overload mechanism is free to function ifexcessive overloading of the circuit should occur. If the knob 23 androd22 are pushed inwardly to the position shown in Fig. 2, both sets ofswitch contacts It, 54 are opened tlius interrupting the circuit in twoplaces and eliminating all possibility of overload. However, when thecircuit is closed d-raival of the wedge 2|, and excessive overloadconditions are established, then the heating coil 33 melts the solderslugs within the solder pot 32' thereby releasing the ratchet wheel illfor free rotation about'the fixed stub shaft 34, and the pawl 35 andslide H are quickly released and urged toward the extreme left as viewedin Fig. 3, thus causing. the fingers 18 to contact the outer ends of thestems l6 and quickly opening both sets of switch contacts 53, M. Thismovement of the overload slide I1. is' produced by the. spring 55-; andin order to thereafter reset the overload device, it is only necessaryto await solidification oi the solder slugs and to subsequently push theknob 23 and wedge 21 inwardly until the wedge 21 coacting with thefingers iii has shifted the slide I! and the pawl 33 backinto engagementwith the teeth of the relocked ratchet wheel 3i. It will thus be notedthat the single wedge 2 l serves not only to effect normal actuation ofthe switch contacts, but is also utilized to reset the overload device,and this wedge in no manner interferes with the automatic functioning ofthe. overload protective mechanism.

From. the foregoing detailed description it must be apparent that mypresent invention provides an; lproved' combined electric switch andoverloadprotective assemblage which is extremely s mple, compact anddurable in construction, and which is moreover highly eiiicient inoperation. The-thermal overload device while being free to functionautomatically and quickly when the switch is closed, can be just asrapidly resetwith the same simple wedge assembly which is normallyemployed to actuate the switch. The same sets of contacts are alsoutilized to make and break the oi uit during both manual and automaticoperation, and additional protection is afforded by utilizing two setsof contacts which may be simultaneously either opened or closed. Theimproved wedge structure also performs its various functions in aneffective manner without subjecting the various parts to undesirablestresses, and serves to equalize the pressures on both of the contactcarrier stems by virtue of its improved construction and mounting. Theswitch assemblage is moreover shock-resistant, moisture-proof, of sturdyand durable construction, while all elements thereof are convenientlyaccessi le for inspection and operation. The ll 'oved switch while beingquickly and conveniently operable cannot be accidentally placed incontacts closed position by shock or bumping of the assemblage. lfhe newswitch mechanism can also be manufactured at moderate cost for use witheither direct or alternating current, and has proven highly satisfactoryand successful in actual use.

While the i roved switch actuating mechanism has been shown anddescribed herein as being applied to a switch having only two sets ofcontacts, it is also applicable to switches having more than two sets ofcontacts and to thermal overload devices having more than one heater,such as shown Furnas Patent No. 2,296,157.

It should be understood that it is not desired to limit this inventionto the exact details of construction or to the precise mode of use,herein shown and described, for various modifications within the scopeof the appended claims may occur to persons skilled in the art.

I claim:

i. In combination, relatively movable switch c acts for closing andopening an electric circu a slide coacting with said contacts and beingoperable thermal overloading to separate said contacts and to therebyautomatically open the circuit, and a wedge havin oppositely inclinedwedge surfaces one of which is normally operable to selectively moresaid contacts in order to effect both c sing and opening or" saidcircuit, of said wedge surfaces being cooper 1 said slide to reset thelatter af er said automatic opening of the circuit.

2. In combination, relatively movable switch contacts for clos ng andopening an electric circuit, a slid, enacting with said contacts andbeing e le by thermal overloading to separate said cts and to therebyautomatically open the circuit, a wedhaving oppositely inclined wedge suce one of i 'hlch is normally operable to selectively move contacts inorder to effect both closing and opening of said circuit, the other ofsaid wedge irfaces being cooperable with said slide to reset the latterafter said automatic opening of the circuit, and manually operable meansfor reciprocating said wedge to effect both normal opening and closingof the circuit and return of said slide to inactive position.

3. In combination, two sets of fixed and movable contacts forsimultaneously making and breaking the same electric circuit, a thermaloverload device for automatically separating the contacts of both setsto break the circuit, and a single wedge having opposite Wedge surfacesone of which is normally movable to separate said contacts and the otherof which is movable to reset said device after automatic operationthereof.

4. In combination, two sets of fixed and movable contacts forsimultaneously making and breaking the same electric circuit, a thermaloverload device for automatically separating the contacts of both setsto break the circuit, a single wedge having one wedge surface normallymovable to separate said contacts and also having an opposite wedgesurface movable to reset said device after automatic operation thereof,and manually actuable means for movin said wedge in like manner duringboth normal making and breaking of said circuit and during resetting ofsaid device following automatic operation thereof. 5. In combination,two sets of fixed and movable contacts for simultaneously making andbreaking the same electric circuit, the movable contacts of said setshavin reciprocal parallel guide stems, a slide movable parallel to saidstems and being normally out of engagement with the stems but cooperabletherewith to move said movable contacts and to break the circuit underoverload conditions, and a wedge movable transversely of the directionof movement of said stems and slide to effect normal movement of saidmovable contacts and to also reset said slide.

-6. In combination, two sets of fixed and movable contacts forsimultaneously making and breaking the same electric circuit, themovable contacts of said sets having reciprocal parallel guide stems, aslide movable parallel to said stems and being normally out ofengagement with the stems but cooperable therewith to move said movablecontacts and to break the circuit under overload conditions, a Wedgemovable transversely of the direction of movement of said stems andslide to efiect normal movement of said movable contacts and to resetsaid slide, and a single wedge movable across said stems and slide tobreak said circuit and to also reset said slide after normal conditionshave been restored.

7. In combination, two sets of fixed and movable contacts, the movablecontacts of said sets having laterally spaced simultaneously movablereciprocable carrier stems, a wedge movable laterally of said stems tosimultaneously move the latter in the same direction, and an actuatingrod for said wedge upon which the wedge is pivotally mounted the pivotalaxis of said rod being disposed transversely of and between said stems.

8. In combination, twosets of fixed and movable contacts, the movablecontacts of said sets having laterally spaced simultaneously movablereciprocable carrier stems, a wedge movable laterally of said stems tosimultaneously move the latter in the same direction, an actuating rodfor said wedge upon which the wedge is pivotally mounted, and anoverload protective device cooperable with the circuit controlled bysaid contacts and havin a tripping slide provided with fingers movablein the planes of reciprocation of said stems, said wedge also beingcooperable with said fingers to reset said device.

9. In combination, two sets of fixed and movable contacts, the movablecontacts of said sets having laterally spaced parallel andsimultaneously reciprocable carrier stems and being spring biased towardclosed position, and a pivotally suspendedwedge movable laterally ofsaid stems and being cooperable therewith to simultaneously open saidmovable contacts the pivotal axis of said wedge being disposedtransversely of and between said stems.

10. In combination, two sets of fixed and movable contacts, the movablecontacts of said sets having laterally spaced parallel andsimultaneously reciprocable carrier stems and being spring biased towardclosed position, a pivotally suspended wedge movable laterally of saidstems and being cooperable therewith to simultaneously open said movablecontacts, and an overload protective device connected in series withsaid contacts and having a tripping slide provided with fingers movablein the planes of reciprocation of said stems, said wedge also beingcooperable with said fingers to simultaneously reset said device and toopen said movable contacts.

11. In combination, a'set of fixed and movable contacts, the movablecontact of said set having a reciprocable carrier stem, a wedgecooperable with the end of said stem to move said movable contact, andan actuating element for moving said wedge, the wedge being pivotallysuspended from said element and the pivotal axis being disposedtransversely of said stem.

12. In combination, a set of fixed and movable contacts, the movablecontact of said set having a reciprocable carrier stem, a wedgecooperable with the end of said stem to move said movable contact, anactuating element for moving said wedge, the wedge being pivotallysuspended from said element, and an overload protective device connectedin the same circuit with said contacts and having a tripping memberprovided with an element movable in'the plane of reciprocation of saidstem, said wedge also being cooperable with said element tosimultaneously reset said device and to open said movable contact.

13. In combination, a set of fixed and movable contacts, the movablecontact of said set having a reciprocable carrier stem, a wedgecooperable with the end of said stem to move said movable contact, anactuating element for moving said wedge, the wedge bein pivotallysuspended from said element, and an overload protective device connectedin the same circuit with said contacts and having a tripping memberprovided with an element movable in the plane of reciprocation of saidstem, said wedge also bein insertible between said stem and element tosimultaneously move said member and said movable contact.

WILLIAM C. FURNAS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Kuhn Jan. 22,

